Reference is made to commonly-assigned U.S. patent application No. D/A1155Q, filed concurrently herewith, entitled INTERNAL AGITATING MECHANISM FOR AGITATING MATERIALS WITHIN SEALED CONTAINERS, by Litwiller.
This invention relates to the packaging and subsequent removal of dry marking materials that tend to clump or bridge when shipped or stored in containers. Dry marking materials such as electrophotographic toners are packaged and shipped in particulate form and other dry marking materials such as dry ink jet waxy solids may be shipped in pelletized or granulated form. Such dry marking materials typically settle and become more densely packed over time. A frequent consequence of such dense packing is often the formation of clumps and bridges formed of the materials within the containers. Agitating and/or aerating the materials before use can restore the desired density, consistency and flow characteristics. The present invention deals with a novel apparatus and method for providing in situ agitation and aeration within a dry marking material cartridge. This apparatus and method obviates the need for human intervention such as shaking or tapping a container, thereby making the degree and type of agitation more reliable.
Although various dry marking materials are contemplated for use with the present invention, the invention will be described in relation to sealed containers that transport and load electrophotographic toners. Other dry marking materials that may benefit from the present invention include, without limitation, waxy colorants, solid ink jet colorants, ionographic inks, and any other dry ink-like product that ships in a substantially non-liquid form.
Generally, in the process of electrostatographic printing, a photoconductive insulating member is charged to a substantially uniform potential to sensitize the surface thereof. The charged portion of the photoconductive insulating layer is thereafter exposed to a light image of an original document to reproduced. This records an electrostatic latent image on the photoconductive member corresponding to the information areas contained within the original document. Alternatively, in a printing application, the electrostatic latent image may be created electronically by exposure of the charged photoconductive layer by an electronically controlled laser beam or light emitting diodes. After recording the electrostatic latent image on the photoconductive member, the latent image is developed by bringing a developer material charged of opposite polarity into contact therewith. In such processes the developer material may comprise a mixture of carrier particles and toner particles or toner particles alone (both these single component and dual component development systems shall hereinafter be called xe2x80x9ctonerxe2x80x9d). Toner particles are attracted to the electrostatic latent image to form a toner powder image that is subsequently transferred to copy sheet and thereafter permanently affixed to copy sheet by fusing.
In such a printing machines, the toner material is consumed in a development process and must be periodically replaced within the development system in order to sustain continuous operation of the machine. Various techniques have been used in the past to replenish the toner supply. Initially, new toner material was added directly from supply bottles or containers by pouring to the developer station located within the body of the automatic reproducing machine. The addition of such gross amounts of toner material altered the triboelectric relationship between the toner and the carrier in the developer station, thereby resulting in reduced charging efficiency of the individual toner particles and accordingly a reduction of the development efficiency when developing the electrostatographic latent image on the image bearing surface. In addition, the pouring process was both wasteful and dirty in that some of the toner particles became airborne and would tend to migrate into the surrounding area and other parts of the machine. Accordingly, separate toner hoppers with a dispensing mechanism for adding the toner from the hopper to the developer station in the printing machines on a regular or as needed basis have been provided. In addition, it has become common practice to provide replenishment toner supplies in a sealed container that, when placed in the printing machine, can be automatically opened to dispense toner into the toner hopper. In some of these designs, the toner cartridge may itself serve as the toner hopper. After this type of toner cartridge is mated to the printing machine at an appropriate receptacle, mechanisms are inserted into the toner cartridge that serve to transport the toner from the toner cartridge into the developer station or an intermediate toner hopper on a regulated basis. See, U.S. Pat. No. 5,903,806 issued to Matsunka et al.; U.S. Pat. No. 5,678,121 issued to Meetze et al.; and U.S. Pat. No. 5,495,323 issued to Meetze.
In any design utilizing a customer replaceable toner cartridge for replenishment, one difficulty that arises is the uniform dispensing of the toner. In particular, toner particles are known to settle and clump during shipment and storage. This clumping phenomenon is caused for a variety of reasons: 1) particles of smaller size can fill and pack spaces between larger articles; 2) toner particles are often tacky; and 3) the electrostatic properties of toner particles enable charge attractions between particles. The result is often agglomerations, or clumps, of particles within the toner cartridge. These agglomerations often compact and form bridging structures within the toner cartridge, and such bridging structures adhere to the sides of the toner cartridges. Simple probes and augers as disclosed in patents such as U.S. Pat. No. 5,903,806 issued to Matsunka et al., U.S. Pat. No. 5,678,121 issued to Meetze et al., and U.S. Pat. No. 5,495,323 issued to Meetze may penetrate such agglomerations and bridging structures but do not break them up. Even rotation of the cartridges after mating onto a printing machine toner receptacle does not impart enough energy to shake the clumped toner particles apart from its various clumps and bridging structures. In the worst case, toner may be entirely prevented from exiting the cartridge unless it is agitated. Since toner cost is a major component of the total cost of printing, any significant amount of toner left in a toner cartridge significantly increases the effective cost of using the printer. Worse, customers that do not receive the expected print volume from a cartridge may assume that the cartridge is faulty and make a warranty claim. In other cases, such customers have been known to make a service call that consumes valuable service and technician time.
In response to the above problems related to removal of substantially all toner from toner cartridges, various devices and procedures have been developed. One effective procedure when performed correctly is simply the shaking of a toner cartridge by human operators prior to mating the cartridge with the printing machine receptacle. However, many operators do not read the instructions and do not know or remember that toner cartridges need to be shaken. In addition, even when human operators read instructions, humans inevitably interpret product instructions subjectively such that an instruction to xe2x80x9cvigorously agitatexe2x80x9d a cartridge may lead to too much force by a few operators and too little by others. The result is that some cartridges are shaken or pounded hard enough to be damaged while others are not shaken enough to break up clumps and bridges that may have formed. Once the cartridge is mated to the receiving receptacle while the toner particles remain clumped and bridged, the operator is left with several choices: One is to leave the cartridge as is and to risk failure of toner transfer from the cartridge, wasting toner and/or believing that the printing system is consuming too much toner. A second choice is removal of the cartridge with its seals open, thereby risking contaminating the toner itself plus spilling the difficult-to-clean particles. A third choice is to try to strike, squeeze, or otherwise agitate the toner cartridge in situ. In addition to the probability that some toner nevertheless remains within the cartridge, such agitation in situ risks damage to the mating receptacle and associated parts of the printing machine. The end result is a frequent waste of valuable toner and a resulting increase in the costs of operating the printing machines plus the risk of warranty and service events.
For toner cartridges that are mounted onto printing machines in order that toner be extracted in a regulated fashion from the cartridges, such cartridges are now often cylindrical in shape with spiral ribs located on the inside peripheral walls of the cartridges. An example of such prior art cartridges is shown in U.S. Pat. No. 5,495,323 issued to Meetze incorporated and is hereby incorporated by reference. See also, U.S. Pat. No. 5,903,806 issued to Matsuoka et al. and U.S. Pat. No. 5,576,816 issued to Staudt et al. that both disclose substantially cylindrical toner cartridges having on their peripheral surface a spiral groove. The toner cartridge and the receiving apparatus operate to rotate the cartridge and to thereby transport the toner within the spiral groove. The apparatus includes a supplying element in the form of an opening and a regulating device. Although toner cartridges with such spiral grooves are effective in urging toward the mouth of the cartridge, such grooves by themselves do little to break up the clumps or bridging described above. Even when the apparatus includes a probe, auger, or similar device that penetrates the stored toner in a cartridge, current designs place such probes only along the central axis of the cartridge. Toner clumped or agglomerated along the periphery of the toner cartridge may not be jostled or mixed by either the rotation of the cartridge or by the probe itself.
Turning now to FIG. 1, a toner cartridge of the prior art is shown. Specifically, FIG. 1 shows the container cap portion 110 of prior art cartridge 90 from U.S. Pat. No. 5,576,816 separated from bottle portion 98. The circumference of container cap 110 is separated into quarters by radial protrusions 112. Pockets 124 are the spaces formed within the ring of container cap 110 by the four protrusions. Bore hole 274 (not labeled in U.S. Pat. No. 5,576,816 is shown at base of the visible portion of protrusions 112. More details concerning bore hole 274 are set forth below in relation to prior art FIG. 2. Experience shows that toner at times becomes packed in pockets 124, particularly when the cartridge has been shipped or stored with that portion of cartridge 110 lower than the rest of the cartridge. Also, no matter how shipped and stored, toner may clump and form bridges in portions of bottle 98. With adequate shaking by human operators prior to installation, such packed, clumped, and bridged toner becomes loose and aerated. However, as discussed above, some operators forget to shake vigorously. Vigorous shaking is particularly necessary when toner powders have packed into pockets 124.
Turning now to prior art FIG. 2, a plan view of the same prior art container shown in FIG. 1 shows more details of container cap 110. In this view, container cap 110 is shown attached to bottle portion 98 of cartridge 90. U.S. Pat. No. 5,576,816 teaches the use of two seals to keep toner particles within bottle 98. Outer seal 136 is a perforable seal filling large outer bore 272. Inner seal 140 fills and seals small bore 274. As taught in U.S. Pat. No. 5,576,816, Inner seal 140 and outer seal 136 cooperate to keep contamination out of cartridge 110 and toner particles within. Specifically, upon installation of cartridge 110 onto the printing system, auger 194, which is contained inside tube 144, perforates outer seal 136 and contacts inner seal 140. Since outer seal 136 comprises flexible elastic material, it maintains a tight seal around tube 144 as tube 144 is pushed further into cartridge 110. Tube 144 has a diameter approximately equal to small bore 274. As auger 194 pushes against inner seal 140, it pushes the seal into the interior of bottle 98. Inner seal 140 may either fall freely into bottle 98 or may remain attached to the tip of auger 194, depending upon the design of inner seal 140 and the tip of auger 194.
Returning to FIG. 1, the long dimension of protrusions 112 is in the direction of and approximately the length of container cap 110. The short dimension of protrusions 112, however, is less than the radius of container cap 110 since at least the diameter of bore 274 must be left unobstructed in order for auger 194 and tube 144 to be pushed into the interior of bottle 98. In the prior art example of protrusions 112 shown in FIG. 1, at least a portion of the long dimension of protrusions 112 extends toward bottle 98 without being attached to the sides of bores 274 or 272. Auger 194 pushes inner seal 140 through this open bore space into the interior of bottle 98. However, since the maximum diameter of inner seal 140 cannot exceed this bore space, nothing in prior art cartridge 90 acts to push or agitate any toner particles that have clumped or bridged inside pockets 124, especially along the outside perimeter of container cap 110. Moreover, since auger 194 remains centered along center line 122, auger 194 does not by itself help agitate or break up clumps and bridges along the perimeter of bottle 98. Even when inner seal 140 is pushed into bottle 98 and left to tumble as cartridge 90 rotates, there is no assurance that tumbling inner seal 140 will contact toner along the entire length of bottle 98. Indeed, spiral rib 104 is designed to urge all tumbling objects inside bottle 98, including both toner and any tumbling inner seal 140, toward container cap 110 rather than toward the end of bottle 98 away from container cap 110. In sum, even prior art cartridges such as cartridge 90 that receive penetrating augers down their center lines are not made with apparatus to agitate toner clumps and bridges formed along the outside perimeter of the cartridge or within pockets of their container caps. The design of these prior art cartridges relies upon human operators to shake and agitate the cartridges prior to installation in order to break apart such clumps and bridges.
At least one prior art device employed a helical member such as a spring inside the toner cartridge for the express purpose of breaking up clumps, bridges, and other agglomerations. In U.S. Pat. No. 4,739,907, issued to Gallant, a cylindrical toner cartridge includes a dispensing opening at one end and an integral toner transport, mixing, and anti-bridging member rotatably supported within the container. The transport, mixing, and anti-bridging member comprises a first coiled spring element having a cross section substantially the same as the cross section of the cartridge and freely rotatable therein, which spring is wound in the direction to transport toner along its length toward the dispensing opening. The member also comprises a second coiled spring element having a cross section substantially smaller than the first spring element but being substantially concentrically positioned and being attached to the first spring element but wound in a direction opposite to the first spring element. In this manner, rotation of the cartridge while the spring members remain substantially fixed results in the scraping of clumped toner from the sides of the cartridge and mixing and penetration of any agglomerations and bridges within the interior of the cartridge by the inner spring.
As described above, conventional toners tend to clump and form bridges. Additionally, recent advances in imaging and toner production have led to smaller toner particles that now may average less than 10 microns. In order to overcome electrostatic forces that tend to attract particles together, a substantial amount of aeration of the toner particles is preferred. It would be advantageous, therefore, to devise a toner cartridge assembly that both aerates toner and that automatically breaks up clumps and bridges within the toner without the need for human operators to shake or otherwise agitate the container prior to installation.
Although the above background for the present invention and several of its embodiments are explained in relation to toner cartridges, the present invention is believed to have wide applicability to any dry marking material prone to clump or form bridges in the shipping cartridge. In particular and without limitation, the present invention applies to dry ink jet marking materials of the type comprised of waxy solid material that marks once melted and placed on the media to be marked.
One embodiment of the present invention comprises a device for storing a supply of marking materials for use in a marking system, comprising: a. an open ended container defining a chamber in communication with the open end thereof with the marking materials being stored in the chamber of said container, said chamber having an end opposite the open end, a center point of such opposite end, a center point of the internal opening at the open end, and an axis running from the center of the opening at the open end to the center of the opposite end; b. an internal seal attached to the open end of said container, said internal seal having a body closely conforming to the internal opening of said container, said internal seal being removable from the open end of said container by displacement of said internal seal into the chamber of said container; and c. a vane attached to the body of said internal seal and extending away from the axis of the chamber.
Another embodiment of the present invention comprises an internal seal for a container for storing a supply of marking materials for use in a marking system, said storage device having an internal opening having a rim, and said internal seal comprising: a. a body closely conforming to the internal opening of the container, said internal seal being removable from the internal opening and said internal seal having a central axis running generally perpendicularly to the rim; and c. a vane attached to the body of the internal seal and extending away from the axis of the body.
Yet another embodiment of the present invention is a marking system with a supply of marking materials, said marking machine comprising: a. an open container defining a chamber in communication with the open end thereof with the marking materials being stored in the chamber of said container, said chamber having an end opposite the open end, a center point of such opposite end, a center point of the internal opening at the open end, and an axis running from the center of the opening at the open end to the center of the opposite end; b. an internal seal attached to the open end of said container, said internal seal having a body closely conforming to the internal opening of said container, said internal seal being removable from the open end of said container by displacement of said internal seal into the chamber of said container; and c. a vane attached to the body of said internal seal and extending away from the axis of the chamber.